1. Field of the Invention
The present invention relates to a monolithic capacitor, and more particularly to a monolithic capacitor including a plurality of capacitor electrodes disposed in a multilayer body, which includes a plurality of dielectric layers stacked in opposing relation with the dielectric layers interposed between the capacitor electrodes, and outer electrodes disposed on at least one surface of the multilayer body and connected to the capacitor electrodes.
2. Description of the Related Art
In a monolithic capacitor in which capacitor electrodes and dielectric layers are stacked, an electrostrictive phenomenon occurs in a capacitor portion and a multilayer body expands and contracts in response to application of a voltage. Recently, with further reduction in size and thickness of the monolithic capacitor, an electric field applied to a dielectric has been increased and the electrostrictive phenomenon has become non-negligible. When an AC voltage including ripples or a DC voltage superimposed with an AC component is applied to the monolithic capacitor mounted (soldered) to a board (substrate), expansion and contraction of the multilayer body are transmitted to the board, whereby the board vibrates. When a frequency of the vibration falls within an audible range of 20 Hz to 20 kHz, the vibration is perceived as audible sounds by the human ear. Such a phenomenon is called “acoustic noise” and causes problems particularly in TVs, notebook personal computers, cellular phones, and so on.
Various proposals have been suggested so far to prevent or reduce the “acoustic noise”. For instance, Japanese Unexamined Patent Application Publication No. 2000-232030 proposes a technique such that ceramic capacitors having equivalent specifications are arranged on front and rear surfaces of a circuit board in a surface-symmetric relationship. With the proposed technique, vibration transmitted to the circuit board from one capacitor and vibration transmitted to the circuit board from the other capacitor cancel each other. As a result, the occurrence of the audible sounds is reduced.
However, the preferred embodiment disclosed in Japanese Unexamined Patent Application Publication No. 2000-232030 has the problem that a degree of freedom in circuit design degrades due to the necessity of mounting two capacitors having equivalent specifications on the front and rear surfaces of the circuit board.